When designing any page, make sure you design for the NATIVE resolution of your devices for the best image possible. First find out what native res your monitor is. Also, reading the res specs for the 100, it looks as if it is designed for 1280x720, but can do 1920x1080. So, if your monitor is native at 1280x720, then this is what you should set your canvas size to in photoshop. 1366x768 is also a close fit to 1280x720. The less that the devices have to scale up or down, the better the picture will be.
Now looking at my numbers, these are for landscape, just flip them for portrait.